Project number: 2017-049
Project Status:
Completed
Budget expenditure: $67,916.04
Principal Investigator: Jaime McAllister
Organisation: University of Tasmania (UTAS)
Project start/end date: 28 Feb 2018 - 30 Nov 2018
Contact:
FRDC

Need

Blacklip abalone remain cryptic for the first 5 to 7 years of life. This life history characteristic of abalone precludes accurate monitoring of the abundance cryptic size classes (juveniles and sub-adults), creating a significant gap in our understanding of abalone population health. This also creates challenges for determining effects on recruitment related to fishing pressure, environmental change, or catastrophic events such as storms, heat waves, or disease. It also creates a significant delay in documenting the effects of remedial actions such as TACC reductions, reseeding, or translocation. Currently determining the effect of a particular management outcome can only be determined 5 to 7 years after an event or management action, at which point attribution of the patterns observed to the event of interest can be difficult if other events have had an effect in that period.

Developing and implementing a repeatable method of determining the abundance of cryptic abalone year classes (2+ to 4+) to enable more timely determination of management actions or acute/chronic external events is a high priority for all Australian abalone fisheries. For the Victorian Eastern Zone Abalone Fishery, there is an urgent need to assess the efficacy of the translocation activities conducted as part of FRDC project 2014-224.

Objectives

1. Test Tasmanian designed juvenile abalone collectors on Victorian Eastern Zone reef systems
2. Use juvenile collector methods to assess effect of translocation on population recovery
3. Consider broader application of juvenile collectors as a recruitment monitoring tool

Final report

ISBN: ISBN 978-1-925646-84-9
Authors: Jaime McAllister Sarah Pyke and Craig Mundy
Final Report • 2019-10-01 • 2.59 MB
2017-049-DLD.pdf

Summary

A new system of Abalone recruitment modules (ARMs) have proven to be successful in collecting juvenile abalone in Tasmanian waters. This design was subsequently transferred to the Eastern Zone, Victoria, where IMAS staff and Eastern Zone Abalone Industry Association (EZIZA) members installed ARMs at four sites with contrasting abalone populations: 1) healthy abalone reef subject to commercial abalone fishing, 2) previously healthy abalone reef that no longer supports abalone populations as it has been denuded by urchins, 3) a site that has been subject to urchin culls to improve abalone habitat but has not had any abalone translocated from elsewhere, and 4) a site that has been subject to urchin culls to improve abalone habitat and has had abalone translocated from elsewhere. After a 6-month deployment the ARMs incurred no major damage and had attracted juvenile abalone across a broad size range (9-91 mm SL) at all four sites. Overall there was a significant difference in abalone density between sites with the highest density recorded at the Petrel Point control site attributed mostly to the higher density of larger individuals (>25 mm SL). In contrast, remaining sites had lower but similar densities except for the Barren site which recorded no individuals larger than 45 mm SL. Small abalone (<25 mm SL) abundances were generally consistent and not significantly different across all four sites. These results demonstrate that both recent and historical spawning events have contributed to maintaining some level of recruitment in these areas, however, suggests there may be some disparity in the survival of recruits between sites.

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